lodash/lodash._createassigner/index.js

/**
 * lodash 3.0.0 (Custom Build) <https://lodash.com/>
 * Build: `lodash modern modularize exports="npm" -o ./`
 * Copyright 2012-2015 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.7.0 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2015 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var bindCallback = require('lodash._bindcallback'),
    isIterateeCall = require('lodash._isiterateecall');

/**
 * Creates a function that assigns properties of source object(s) to a given
 * destination object.
 *
 * @private
 * @param {Function} assigner The function to assign values.
 * @returns {Function} Returns the new assigner function.
 */
function createAssigner(assigner) {
  return function() {
    var length = arguments.length,
        object = arguments[0];

    if (length < 2 || object == null) {
      return object;
    }
    if (length > 3 && isIterateeCall(arguments[1], arguments[2], arguments[3])) {
      length = 2;
    }
    // Juggle arguments.
    if (length > 3 && typeof arguments[length - 2] == 'function') {
      var customizer = bindCallback(arguments[--length - 1], arguments[length--], 5);
    } else if (length > 2 && typeof arguments[length - 1] == 'function') {
      customizer = arguments[--length];
    }
    var index = 0;
    while (++index < length) {
      var source = arguments[index];
      if (source) {
        assigner(object, source, customizer);
      }
    }
    return object;
  };
}

module.exports = createAssigner;